Atypical plasma processing system is used for etching, deposition and so forth. A plasma processing system of this type comprises, e.g., top and bottom electrodes provided in parallel to each other in a processing chamber, and is designed to apply a high-frequency power to the bottom electrode and feed a process gas into the processing chamber to produce the plasma of the process gas by discharge between the top and bottom electrodes to carry out a predetermined plasma processing for a processing object, such as a semiconductor wafer. However, by-products are produced from the process gas during the plasma processing, and these by-products are deposited on the wall surfaces and the top and bottom electrodes in the system to form deposited films. Since the deposited films cause particles if leaving them as they are, the interior of the system is cleaned at the right time to remove the deposited films. In addition, consumable supplies, such as a focus ring, are used in the plasma processing system. These consumable supplies are under attack from the plasma to be consumed. For that reason, the consumable supplies are exchanged during maintenance, such as cleaning.
However, any methods for measuring the thickness of deposited films without opening the processing chamber of a plasma processing system are not known. Therefore, timing in removing the deposited films, i.e., cleaning timing, must be determined by trusting operator's experience and intuition. In addition, the kind of the deposited films varies in accordance with the kind of the process gas, and the growth rates of the respective deposited films are different, so that it is next to impossible to appropriately predict a cleaning period.
Moreover, the consumed degrees of consumable supplies vary in accordance with the processing contents similar to the growth rates of the deposited films, and any methods for predicting the consumed degree of consumable supplies without opening the processing chamber are not known, so that the consumable supplies must be exchanged during maintenance.